Various types of screen with a sheet-like flexible screen body have been proposed within the industry. Typically, image lights are magnified and projected from a projector or others onto a screen projection surface of the screen body as referred to in Japanese Patent No. JP-A-11-142974.
The screen disclosed in the Japanese Patent No. JP-A-11-142974 is a transportable screen whose body is wound up when stored and is pulled out to form a projection surface when the screen is in use. More specifically, the transportable-type screen disclosed in the Japanese Patent No. JP-A-11-142974 is configured to include first and second frames, a spring roll, and extension means. The spring roll is attached to the first frame for taking up the screen body. The second frame is fixedly attached with an end of the screen body, and the extension means biases both the first and second frames in a direction of moving the frames away from each other. The extension means is configured to include first to fourth rails, and an elastic member. The first and fourth rails extend parallel to each other, and their one ends are respectively attached pivotally to the first and second frames. The second and third rails also extend parallel to each other, and their one ends are each pivotally attached to the first rail, and their other ends are each pivotally attached to the fourth rail. The elastic member is latched by, at one end, the pivotally-attached portions of the first and third rails, and the other end is latched by the pivotally-attached portions of the second and fourth rails.
For using the screen, a user applies a force in a direction of moving the first and second frames away from each other so that the extension means is extended, and the screen body is pulled out from the spring roll. When the screen is not in use, the user applies a force in a direction of moving the first and second frames close to each other so that the extension means is folded, and the screen body is wound up by the spring roll. That is, the extension means has a function of guiding the first and second frames to be close to or away from each other.
Among other things, one problem with such a transportable screen as disclosed in the Japanese Patent No. JP-A-11-142974 is that the configuration of the extension means is complicated and not easy to be simplified as it is configured by the four rails and the elastic member.